The wordplay is interesting: He discerned that Christ would return invisibly and that “the appointed times of the nations” would end in 1914.
In a certain way, the sentence is technically true. Russell taught Christ had returned invisibly in 1874 and he believed the Gentile times would end in 1914. Of course, it is highly misleading...the rank and file would read this as Russell teaching the invisible presence would begin in 1914.
But then again, they just said they could err. They just demonstrated it.